1. Field of the Invention
The present invention relates to a color CRT (Cathode Ray Tube) integrated with deflection circuit, and more particularly, to a color CRT having a deflection circuit formed integrally with the color CRT for driving a deflection yoke mounted on the color CRT by previously removing the causes of fluctuation of the deflection yoke according to the change of set conditions, without mounting on a substrate having a video signal processor of a chassis.
2. Description of the Related Art
As shown in FIG. 1, a color CRT (Cathode Ray Tube) includes a panel 16 mounted on a front surface of the CRT, a fluorescent surface 15 coated with phosphor of R (Red), G (Green) and B (Blue) colors on the inner surface of the panel, a shadow mask 14 disposed on a rear portion of the fluorescent surface and serving to select color of the electron beams incident on the fluorescent surface, a funnel 13 connected to a rear portion of the panel and maintaining the inside of the funnel in a vacuum condition, an electron gun 11 mounted in the inside of a neck part of a tube type disposed at a rear portion of the funnel for emitting the electron beams, and a deflection yoke 20 surrounding the outside of the funnel 13 and mounted for deflecting the electron beams horizontally or vertically.
The deflection yoke 20 includes a horizontal deflection coil 21, a vertical deflection coil 22, a ferrite core 23, a holder 24 and a compensating circuit board 25. As shown in FIG. 3, a compensating circuit is divided into a compensating circuit using the vertical deflection coil and a vertical deflection current and another compensating circuit using a horizontal deflection coil and a horizontal deflection current. For the compensating circuit using the vertical deflection current, there are a tilt compensating circuit, an YBH (Y-axis Bow Horizontal) compensating circuit, an YCH (Y-axis Cross Horizontal) compensating circuit, a 4 poles CY (Convergence Yoke) coil, a CCV (Corner Cross Vertical) MCM (Magnetic Current Modulation), an inner MCM (Magnetic Current Modulation), and so on. For the compensating circuit using the horizontal deflection current, there are a balance coil, a cancel coil, a CCV MCM, an inner MCM, and so on. The tilt compensating circuit has a variable resistance R16, which is connected in series between resistances R1 and R2, connected to vertical deflection coils L1 and L2. The YBH compensating circuit includes a variable resistance R7 connected in series to the vertical deflection coil, four rectifying diodes D1, D2, D3 and D4 connected in rows to the variable resistance, a compensating coil L4 connected in rows to the rectifying diode D2 and another compensating coil L5 connected in rows to the diode D1.
The YCH compensating circuit is connected in rows to resistances R10 and R13 and adjusts a variable resistance R12 by current flowing in a resistance R11. The 4 poles CY coils L6 and L7 are connected in rows to the diode D4 and the resistance R9 connected in series, to the diode D3 and a resistance R14 connected in series, and coils L4 and L5 connected in rows. The inner MCM L8 is connected in rows to a resistance R15 and connected to the 4 poles CY coils L6 and L7.
A conventional deflection yoke makes horizontal deflection currents Ih (+) and Ih (xe2x88x92) of a several ampere [A], which has frequency of 15.75 KHz or more, flow into the horizontal deflection coil and deflects the electron beams inside the color CRT horizontally using magnetic field generated by the horizontal deflection currents. Moreover, the conventional deflection yoke makes vertical deflection currents Iv (+) and Iv (xe2x88x92) of about 1[A], which has frequency of 60 Hz, flow into the vertical deflection coil and deflects the electron beams vertically using magnetic field generated by the vertical deflection currents. A self convergence type deflection yoke adjusts winding distribution of the horizontal deflection coil and the vertical deflection coil and makes barrel or pin-cushion type magnetic fields by each part (i.e., an opening part, a center part and a neck part), so that the barrel or pin-cushion type magnetic fields are converged on the same point from different distances, i.e., on a screen being a arrival place from a starting place. Because only before-mentioned deflection coil cannot satisfy laster distortion and convergence characteristics due to flatness, scale-up and high resolution of the screen, the convergence characteristics are adjusted using the convergence compensating circuit. To compensate misconvergence, such as YBH, YCH, tilt, VCR and others, occurred due to the flatness of the screen, a convergence compensating circuit 25 including a full-wave rectifying circuit, a balance coil and a CY coil using the diodes is mounted on the neck part of the deflection yoke.
Furthermore, in case that the current is flowed in the deflection coil to make the magnetic field, a ferrite core of high permeability is used to minimize a loss in a feedback path of the magnetic field, thereby increasing the magnetic field efficiency and the magnetic force. The variable resistance R16 adjusts an amount of current flowing in right and left vertical deflection coils to compensate the tilt. To compensate the inner MCM and the CCV (Corner Cross Vertical), auxiliary coils L3 and L8 for compensating the MCM are connected in series to the vertical deflection current for synchronizing the horizontal deflection current and the vertical deflection current. To compensate the YCH, the variable resistance R12 adjusts the current flowing in the auxiliary compensating coils L4 and L5, and YBH compensation amounts of 12 o""clock direction and 6 o""clock direction are adjusted. Moreover, to compensate the YBH, the variable resistance R7 is adjusted to adjust the current flowing in the auxiliary compensating coils L4 and L5. To compensate the VCR, the auxiliary compensating coils L6 and L7 are connected in series to the vertical deflection coil.
The balance coil L13 adjusts the currents of the upper and lower horizontal deflection coil, so that the screen distortion due to the linear symmetry of the horizontal deflection coil is compensated. Auxiliary coils L10 and L12 for compensating the CCV is connected to the horizontal deflection coil connected in parallel to compensate the CCV and is connected in series to the horizontal deflection coils L9 and L10 connected in parallel to compensate the inner pin-cushion.
The compensating circuits attached on the conventional deflection yoke have a restricted use only for adjusting the convergence characteristics.
Moreover, conventional color CRTs do not have the deflection circuits of oneself, differently from display devices such as LCDs or PDPs, and therefore, it is necessary to adjust the characteristics of the deflection yoke according to consumers"" development styles when being manufactured. Generally, in a supply and demand condition that a yearly consumption of the color CRTs by the consumers is maximally tens of thousands and a yearly production of the color CRTs by suppliers is at least one million, the present system that must change the manufacturing conditions of suppliers according to the demand of consumers is very irrational.
The present system will be described hereinafter in more detail. A color CRT provider provides tubes, on each of which a deflection yoke is mounted, to a consumer, i.e., a set manufacturer, and the set manufacturer applies them to a new model using a chassis deflection circuit, which is old model. At this time, for impedance matching between the provided deflection yoke and the deflection circuit of the chassis, the set manufacturer requires an adjustment in characteristic of the deflection yoke to the color CRT provider. To adjust the characteristic of the deflection yoke, especially, inductance (L), the number of turns of the deflection coil must be adjusted. As a result, a mechanical dimension of the deflection coil is changed, thereby causing mislanding, i.e., purity characteristic of the color CRT. Additionally, because it is difficult to obtain the same screen characteristic if the inductance is changed, there are 10xcx9c30 kinds of the deflection yoke for one model of the color CRT, which is the same number as the set manufacturers. In this case, because a large number of deflection yokes must be manufactured for one model of the color CRT, the quality and productivity of the deflection yoke are deteriorated and the maintenance cost of the model is increased.
It is, therefore, an object of the present invention to provide a color CRT (Cathode Ray Tube) integrated with deflection circuit for allowing a one-to-one matching of the deflection circuit and a deflection yoke by attaching a sync signal separation and deflection circuit on at least a portion of the color CRT and by previously removing the causes of DY fluctuation due to the change of set condition.
It is another object of the present invention to provide a color CRT integrated with deflection circuit for allowing a reduction of manufacturing cost by mass production of the deflection circuit and the deflection yoke and improvement of quality.
To achieve the above objects, the present invention provides a color CRT (Cathode Ray Tube) integrated with deflection circuit, the color CRT, which includes an electron gun emitting three electron beams of R, G and B colors, a deflection yoke having a horizontal deflection coil and a vertical deflection coil for deflecting the electron beams to a designated place of a screen, a shadow mask for selecting colors by sorting the electron beams of the three colors, and the screen for emitting light by a collision of the electron beams onto a fluorescent surface, said color CRT comprising: a sync signal separation and deflection circuit board attached on at least a portion of the color CRT, the sync signal separation and deflection circuit board including a sync signal separation circuit for separating sync signal from video signal to represent video signal into the same contents, a horizontal deflection circuit for applying horizontal deflection current onto a horizontal deflection coil and a vertical deflection circuit for applying vertical deflection current onto a vertical deflection coil.
Preferably, the sync signal separation and deflection circuit board further includes a compensating circuit formed thereon, and the circuit board is attached on at least a portion of the color CRT.
Moreover, a portion of the sync signal separation and deflection circuit board is fixed on a funnel part of a tube, fixed and supported on the deflection yoke, disposed parallel to a longer side or a shorter side of the color CRT panel, fixed and supported on the deflection yoke and the funnel part between a high voltage applying part and the deflection yoke, or fixed and supported on a neck part and the deflection yoke or the funnel part.
According to another embodiment, the present invention provides a color CRT (Cathode Ray Tube) integrated with deflection circuit, the color CRT, which includes an electron gun emitting three electron beams of R, G and B colors, a deflection yoke having a horizontal deflection coil and a vertical deflection coil for deflecting the electron beams to a designated place of a screen, a shadow mask for selecting colors by sorting the electron beams of the three colors, and the screen for emitting light by a collision of the electron beams onto a fluorescent surface, the color CRT comprising: a deflection circuit part attached on at least a portion of the color CRT, the deflection circuit part including a horizontal deflection circuit for applying horizontal deflection current onto a horizontal deflection coil and a vertical deflection circuit for applying vertical deflection current onto a vertical deflection coil, wherein the deflection yoke and the deflection circuit part are in one-to-one impedance matching to each other before being attached on the color CRT and selected arbitrarily from mass-produced deflection yokes and deflection circuits respectively.
According to a further embodiment, the present invention provides a color CRT (Cathode Ray Tube) integrated with deflection circuit, the color CRT, which includes an electron gun emitting three electron beams of R, G and B colors, a deflection yoke having a horizontal deflection coil and a vertical deflection coil for deflecting the electron beams to a designated place of a screen, a shadow mask for selecting colors by sorting the electron beams of the three colors, and the screen for emitting light by a collision of the electron beams onto a fluorescent surface, the color CRT comprising: a deflection circuit part attached integrally with the color CRT, the deflection circuit part including: a sync signal separation circuit for separating sync signal from video signal to represent video signal into the same contents; horizontal and vertical oscillation circuits for making horizontal and vertical oscillating signals of square wave by using horizontal and vertical sync signals separated from a sync signal separating circuit or oscillation wave; a horizontal drive circuit for amplifying small output of the horizontal oscillation circuit for a horizontal output circuit for high current switching; a vertical drive circuit for improving an amplification degree and a linearity of the vertical deflection circuit and for actuating the circuit stably; a horizontal output circuit for making saw-tooth wave horizontal deflection current used for deflecting the electron beams horizontally and for making and providing high voltage pulse with a fly back transformer (high voltage generator); a vertical output circuit for making saw-tooth wave horizontal deflection current for deflecting the electron beams vertically; an AFC (Automatic Frequency Control) circuit mounted for obtaining a stable screen by detecting a phase difference between sync signal and horizontal output signal and by controlling the oscillation circuit; and an E/W (East/West) distortion compensating circuit for compensating lateral distortion of a screen pattern.
Preferably, the sync signal separation and deflection circuit board or the deflection circuit part further includes at least one of a signal impressed connection part for connecting the sync signal separation and deflection circuit board or the deflection circuit part to a high voltage circuit part mounted on a chassis and a high voltage impressed connection part for connecting the sync signal separation and deflection circuit board or the deflection circuit part to a high voltage circuit part mounted on the chassis. Alternatively, the signal impressed connection part and the high-tension circuit part may be made with an integrated connection part.